The shooter walked into the gym at Berrendo Middle School around 8 a.m. and shot an 11-year-old boy and a 13-year-old girl before a teacher stopped the attack, the Associated Press reports.

Martinez said the attack was “quickly stopped by one staff member who walked right up to him and asked him to set down the firearm, which he did.”

Officials at University Medical Center in Lubbock, Texas, said the boy arrived at the center by airlift and remains in critical condition. The girl victim was en route to the hospital and was in serious condition, they said.

Governor Martinez added that a staff member also sustained minor injuries.

State police identified the shooter as a seventh-grader, and KOB4 reports that authorities have a suspect in custody.